In order for the braking system of a vehicle to operate in an effective and safe manner, it is important that the master brake cylinder assembly be purged of any gas which might have become entrapped therein. Various devices have heretofore been utilized in an effort to effect such purging or bleeding of the gas; however, because of certain inherent design characteristics they have been beset with one or more of the following shortcomings: (a) they were of complex, bulky and costly construction; (b) they were difficult and awkward to operate; (c) they were unreliable in properly performing the required purging operation; and (d) they required an inordinate amount of servicing.